Weight?
My truck 04 RC-SB silverado 1500
if I put a LQ4 in can I use my 4.8 heads?
can I hit a goal of 600HP and still drive her back and forth to work?
Say both are in front of you but you only have enough money for one, which one you taking home?
I'm thinkin the LS-6.

 

Cubes and compression , Do a lq4 with ls6 heads if you want to keep it all gm.

 

go LQ4!!! ls6 is just an ls1 with different heads and cam. Buy the lq4 get a set of ls6 heads and get yourself a big thumpr cam for the same price of the ls6. Im doing the same thing at the moment. Youll be around 400+ hrsp everyday and well throw a 150 shot on her and yourr pretty darrrn close to that 600 goal your talking about and driving it everyday

 

I'd go with as much displacement as possible. Preferably 7 liters minimum.,

 

The only substitute for cubic inches is more cubic inches

 

Cubic Feet

 

So, 6.0 liter it is, could I still use my 4.8 heads?

 

IF your looking for 600 hp the 6.2 with l92's and roots style blower. At least thats how the ZR1 got there...
Do you have any idea whats gonna be involved in making 600 rear wheel horse? You can pretty much plan on scraping your drivetrain, (if your gonna drive it). Whats the point of going to more cubes unlss your gonna get l92's. Keep the 4.8 put, 317's on it and bring your compression way down then boost the **** out of it and be happy with what ever it make's. Your gonna have to drive it around on DOT drag radials, to be able to use anything over 400...

 

In my opinion, it depends what your goals and budget it. Sure the lq4 is slightly larger, but the aluminum block weighs about 80 pounds less which is a notable difference. The ls6 in my opinion is better suited for an n/a build and the lq4 is better suited for forced induction when you're on a reasonable budget.

However, in order to obtain 600 rwhp numbers I would go with the lq4 and turbo it. That would be the cheapest and most efficient route to 600 rwhp without nitrous.

 

Get KB to hook you up with a ice Turbo kit